German period tracking app Clue has over 2.5 million active users — but it's still not sure how it's going to make money

Ask Ida Tin what her goal is, and she struggles to come up with
just one. The top of the App Store's health and fitness section
would be nice, she says (she's only got to third place before) —
or maybe helping every woman on the planet track their
reproductive health.

It sounds ambitious, but her female reproductive health app
Clue has quickly spread around the world from its launch in
Berlin, and now has over 2.5 million active users. Even Apple
came to her for help with its own software.

Clue is a period tracking app that uses data inputted by the user
to give insight into their cycle. Women input information about
their mood, sexual activity, pain, and bleeding, as well as other
things. The app uses that to work out their cycle and give them
information about it.

Clue.Clue

The Clue app has a modern design, and users of the app that
Business Insider talked to explained that its colourful, almost
playful, nature is a reason why they keep using it. "People like
that it’s not pink or overly girly," Tin said. "It's not
patronising."

That's in contrast to the appearance of apps like Period Diary,
Clue's biggest competitor in the App Store:

Period
Diary

Tin emphasises that users can share their data with the app's
servers, or they can keep it to themselves, storing it offline.
It can also be synchronised with Apple's HealthKit platform,
which stores health data from lots of different apps.

"Maybe they just forgot," Tin says of Apple's decision to release
a health tracking app without any period tracking. However, she
says that after Apple realised its mistake, it immediately set
about trying to make it right. Tin says Clue worked with Apple to
help it develop its own period tracking software — essentially
creating a competitor to her own app.

"I felt we had a really constructive dialogue with them, helping
them figure out what the core things that should go in are," Tin
says. "We had an ongoing conversation about what should be there.
I felt that they listened."

Apple eventually
released an updated health app in June that featured full
support for period tracking and female reproductive health. Users
could manually add their periods and sexual activity, and Clue's
data synced with the app. Clue suddenly had a major new
competitor, but it also had a new platform for women to examine
their data on.

Clue is also available for women to install on their Apple Watch.
Right now that's a pretty niche feature for an app to have, but
Tin says that the Apple Watch is a good way for women to get
notifications from the app.

She does recognise, however, that the Apple Watch is still a
limited platform: "I think our product is very much the first
generation MVP (minimum viable product), I think we can probably
do a better job. But I do think it’s interesting."

Another thing that Clue is trying out is a series of partnerships
with universities and medical institutions. It's working with
Stanford University, Columbia University, the University of
Washington, and the University of Oxford to provide data for
studies. "What they get excited about is having a data set which
is so large compared to what clinical studies were before," Tin
says.

Clue is clearly out to help women and doctors learn more about
female reproductive health, but if it wants to spread around the
world, it needs to start making money. Right now the app is free,
and Tin says that the company doesn't know how it's going to
monetise. However, she does know how she doesn't want to do it:
selling user data or introducing ads to the app.

"There are probably many more things that we could do [to make
money]," Tin said. "But we are taking our time now to grow and
make little experiments with monetisation." She suggested that
one way Clue could make money would be charging for more in-depth
data-driven information or detailed health advice.